1. Technical Field
The present invention relates generally to an image processing apparatus and a program, in particular, an image processing apparatus capable of synthesizing a plurality of sub-images in a panoramic way and creating a panoramic image, and an image processing program capable of serving a computer as an image processing apparatus.
2. Related Art
In the past, for such an image processing apparatus, an approach in which a plurality of images photographed by a digital camera is corrected by adjusting brightness or a contrast etc. is proposed (for example, see JP-A-2000-215306). Further, for such an image processing apparatus, another approach is proposed, in which all images are corrected based on the correction parameter obtained from one image, in addition to correcting each image respectively based on a correction parameter obtained by interpreting a pixel sampled from a plurality of images (for example, see JP-A-2007-164247). Specifically, the desired item is established out of brightness or chroma etc., an image in which the value of the established item approximates to the average value is selected by interpreting a plurality of images, and a correction parameter is established by interpreting the selected image. Subsequently, all images are corrected based on the thus established correction parameter, and thereby the image quality between the respective images can be prevented from, to a large extent, being non-uniform after the correction of the plurality of images.
Nonetheless, when a panoramic image is created by synthesizing a plurality of sub-images in a panoramic way, it is required that the entire panoramic image is corrected using the same correction parameter not so as to change to a great extent the brightness or chroma etc. of a part of the panoramic image. In this case, even though a correction parameter can be obtained by interpreting pixels sampled from the panoramic image in which sub-images are synthesized in a panoramic way, it takes much more time to synthesize all the sub-images because the panoramic image is larger than the sub-images before synthesization. Thus, in order to reduce the synthesization time, similarly to the image processing apparatus described above, it is considered that the correction parameter is set up by selecting one sub-image from a plurality of sub-images and interpreting the selected sub-image. Nevertheless, even though the correction parameter is established simply by selecting an sub-image in which the value of an item such as brightness, chroma, etc. approximates the average value, it is difficult to accomplish user-desired image correction because an attractive main portion exists in the panoramic image and the sub-images corresponding to the main portion are a portion of a plurality of sub-images.